From Nature magazine

It may just look like your average rock, but in fact it's an extra-special delivery from the red planet. Laboratory analysis has revealed that a specimen bought from a Moroccan meteorite dealer in 2011 is the first sample of Martian origin that is similar to the water-rich rocks examined by NASA’s rovers.

The meteorite, dubbed Northwest Africa (NWA) 7034, contains a concentration of water by weight about ten times higher than in any of the other 100 or so known Martian meteorites — those rare rocks that get ejected from the Martian surface into space when an asteroid hits the planet, and eventually find their way to Earth. It’s also the only known Martian sample on Earth that hails from a critical period, about 2 billion years ago, when Mars is thought to have become colder and drier than it was originally.

Carl Agee of the University of New Mexico in Albuquerque and his colleagues report their findings from samples of the meteorite in Science online today.

Water clues

“Agee and his collaborators have thrown open the door to a whole new part of Mars,” says planetary scientist Munir Humayun at Florida State University in Tallahassee, who was not involved in the study. The meteorite, he adds, is “the first of a new class of Martian meteorites that provides more direct clues to the surface history of Mars.”

Moreover, Humayun says, NWA 7034 may provide the only direct corroboration for the rovers’ observations for some time to come, as the fate of a long-delayed mission to bring samples of Mars back to Earth is still uncertain.

The elemental composition of the meteorite strongly resembles that of rocks examined in 2005 by NASA’s Spirit rover at Gusev Crater. Those rocks showed evidence of chemical alteration by interactions with liquid water, notes Agee. The composition of NWA 7034 also matches that of rocks studied by Curiosity, NASA’s newest rover, as described in preliminary reports from members of that mission.

Missing link

Dating from 2.1 billion years ago, NWA 7034 is the second-oldest Martian meteorite, and provides a "missing link" in the planet’s geological record, according to Agee. (The oldest prospective Martian meteorite, ALH 84001, is 4.5 billion years old, whereas all other Martian meteorites are 1.3 billion years old or younger.) Several lines of evidence indicate that parts of Mars were warmer and wetter, and therefore a possible haven for carbon-based life, some 4 billion years ago. The relatively high water content of NWA 7034, which could be as much as 0.6% by weight, suggests that “crustal or surface processes involving water may have lasted” well beyond the 4-billion-year mark, Agee adds.

That is not a surprise, given the map of hydrogen (a stand-in for water) generated by an instrument on the Mars Odyssey orbiting spacecraft and the presence of small amounts of water in younger Martian meteorites, notes Harry McSween at the University of Tennessee in Knoxville.

The meteorite is made of volcanic rock, and the presence of water in it suggests that crustal rocks on Mars interacted with surface water that was delivered by volcanic activity, near-surface reservoirs or by impacting comets, Agee says. But Jeffrey Taylor of the University of Hawaii in Honolulu says that whether that water content truly reveals an abundance of surface water on Mars 2.1 billion years ago awaits further study.

This article is reproduced with permission from the magazine Nature. The article was first published on January 3, 2012.

11 Comments

1. 1. Wladik 02:55 AM 1/4/13

   The origin of water needs more explanation.
   1. the way from the Mars to Earth takes a long time, all original water can evaporate;
   2. there is cosmic rays that can implant some protons into the rock;
   3. was there an ocean 2 billions years ago at the place of meteorite? The Earth's water can penetrate through diffision.

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2. 2. vinodkumarsehgal 08:17 AM 1/4/13

   "Several lines of evidence indicate that parts of Mars were warmer and wetter, and therefore a possible haven for carbon-based life, some 4 billion years ago."
   
   Astronomers estimate Sun to have formed some 4.6 billion years ago and age of earth is estimated at about 4.5 billion years ago. All the planets ( at least inner planets) of Solar system are understood to have been created from a common gaseous protoplanetary disc of Sun. In this respect, age of Mars should also be in the range of 4.5 billion years. When Mars separated from common gaseous protoplanetary disc as a gas lump some 4.5 billion years ago, how it could become wetter ( implying possessing water) and warmer and became haven for hosting carbon based life 4 billion years ago. Within a span of some 500 million years, could water or even oceans of water could come into existence from rotating gaseous body?

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3. 3. Bill_Crofut 03:43 PM 1/4/13

   Re: "...Martian meteorites—-those rare rocks that get ejected from the Martian surface into space when an asteroid hits the planet, and eventually find their way to Earth."
   
   It would be interesting to know what experiment has been conducted to demonstrate that any impact event could eject a martian rock into space and place it on a trajectory that would result in the rock being deposited on Earth.
   

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4. 4. Daniel35 10:55 PM 1/5/13

   I agree with Bill_Crofut. How can they tell for sure that it comes from Mars? How many of such have been found? Are there also some from the moon, other planets or asteroids? Well, I guess they're all asteroids once their in space.

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5. 5. Stuka1944 12:58 PM 1/6/13

   While any scientific discovery should to some extent be doubted, I think doubt is being placed in the wrong places here. It would be relatively easy to determine if the meteorite originally came from mars or not(comparing soil composition to that of mars). But I don't see the water evaporating when it's frozen solid in 2K space. The best question that has been posted was whether or not the rocks could be ejected from Mars atmosphere, which I see as plausible but I doubt real experiment has been done to test it, likely computer simulations.

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6. 6. Bill_Crofut 08:21 AM 1/7/13

   Daniel35,
   
   Thank you for your support. This is not my first experience challenging the bolide impact/ejection assertion for alleged martian rocks on the surface of the Earth. The other side of the challenge is in the form of a question: Since the rocks have been found on Earth, where is the evidence that they were not always earthen rocks? My problem with computer simulations (as the father of a software engineer) is the unavoidable condition of input bias. A computer is only going to give back information as good as the information that was programmed into it.
   

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7. 7. bucketofsquid in reply to Bill_Crofut 09:18 AM 1/8/13

   At the moment I'm impartial to the origin of the rock because I have no idea of the physics involved but what I can say with certainty is that bias and careless formula coding and testing can lead to some wildly inaccurate results. I've had software tested and in production for years before someone finds an error. Since humans want to branch out from Earth eventually, the only real solution is to crash an asteroid of the appropriate size into Mars and see if something is ejected. One of the Mars terraforming concepts involves doing that anyway so why not?

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8. 8. e_caroline 01:10 PM 1/8/13

   It seems premature to be too certain of the origin of items that have been in interplanetary space for untold eons of time.
   
   I know it is all kinds of sexy to think that one can explore Mars without going there but it truly seems we know far too little about the details of the particular planets that formed in this solar system to be all that certain we can intuit the ancient, ancient history of a planet that we have only barely touched with equipment able to examine it.

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9. 9. Bill_Crofut 08:37 AM 1/9/13

   bucketofsquid,
   
   Re: "...the only real solution is to crash an asteroid of the appropriate size into Mars and see if something is ejected."
   
   You've precisely stated my point. That would at least be a test of the hypothesis that such an event could happen.
   

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10. 10. vinodkumarsehgal in reply to Bill_Crofut 04:51 AM 1/10/13

    Even if it is empirically established that on collision, something ejects out of Mars, what is the certainty that that ejected piece shall fall here on earth?

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11. 11. Bill_Crofut 07:57 AM 1/10/13

    vinodkumarsehgal,
    
    You've precisely emphasized the skeptical side of my point. There is no certainty that any ejected material would reach Earth. In fact, my skepticism goes deeper than that; an objection to the martian label attached to each of a few meteorites that have been discovered. Since the meteorites have been found on Earth, what is the evidence that they were not always earthen rocks?
    

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